Write a script to display the first three self-descriptive numbers.
say '1210, 2020, 21200'. On to the next task. Not so quickly 🙂 While the above would produce the expected output, that’s not the spirit of what the weekly challenge is about.
For this task I ran an incrementing loop that exited once three self-descriptive numbers were found. The main part of the logic appears in the
_is_self_descriptive subroutine. I first convert the number into an array of occurrences. For example
12140 would be turned into
1,2,1,0,1,0,0,0,0,0. I then compare this with the digit in the position, and return false
undef or true
1 if there is a match.
» ./ch-1.pl 1210, 2020, 21200
Write a script to list methods of a package/class.
For caveats first.
- In the real world, I would simply use Class::Inspector‘s
methodsfunction. There is no need to re-invent a perfectly working wheel.
- My solution won’t list inherited methods. We could walk the
@ISAtree, but this seems more complicated than required for the task.
- Likewise it won’t show autoloaded methods.
- My code is loosely based on Class::Inspector
And with all of that, there isn’t much else to say. I
require the package, and then look up everything in its table, and exclude everything that it’s a sub-routine (e.g variables).
If a package is not supplied, then
Calc is assumed.
» perl -I . ./ch-2.pl div new add mul